Passivating contacts for silicon solar cells based on boron-diffused recrystallized amorphous silicon and thin dielectric interlayers

• Published in: Solar energy materials and solar cells Vol. 152; pp. 73 - 79
• Main Authors: Yan, Di, Cuevas, Andres, Wan, Yimao, Bullock, James
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2016
• Subjects: Amorphous silicon; Boron; Contact; Diffusion; Electrical resistivity; Interlayers; Passivated contact; Photovoltaic cells; Polysilicon; Silicon dioxide; Solar cell; Solar cells; Solar cell; Amorphous silicon; Boron; Polysilicon; Passivated contact
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.03.033

A technique to make poly-Si (p+)/SiOx contacts for crystalline silicon solar cells based on doping PECVD intrinsic amorphous silicon (a-Si) by means of a thermal BBr3 diffusion process is demonstrated. The thickness of the a-Si layer and the temperature of the boron diffusion are optimized in terms of suppressing carrier recombination and transport losses. Different interfacial layers are studied, including ultra-thin SiOx grown either chemically or thermally, and stacks of SiOx and SiNx. While the double SiOx/SiNx interlayers do not achieve the desired performance, both kinds of single SiOx layers produce satisfactory passivating contacts, with both a low recombination current and a low contact resistivity. By adjusting the boron diffusion temperature, recombination current parameter J0 values of ~16fA/cm2 to ~30fA/cm2 have been obtained for structures with initial a-Si thicknesses of 36–46nm, together with a contact resistivity of ~8mΩcm2. •It describes a technique to make poly-Si contacts based on BBr3 diffusion and intrinsic a-Si.•The thickness of a-Si and temperature of boron diffusion are optimized.•We studied different interfacial layers, including single SiOx and stacks of SiOx and SiNx.•The degradation observed after FGA can be solved by doping poly-Si contacts.